The use of ultrafiltration (UF) to treat pulp mill effluents is limited by fouling of membrane surfaces and pores. In prior studies with pulp mill effluents, no efforts were made to relate the molecular-size distribution of the solute molecules to the membrane fouling mechanisms. This dissertation presents a novel protocol for obtaining certain essential size distribution parameters, such as, the average molecular weight (M(w)), average molecular number (M(n)) and heterogeneity index (HI) to describe complex industrial wastewaters including the extraction (E)-stage effluent. This novel molecular sizing protocol was verified using challenge solutions containing solutes of known molecular weight. In these tests, the measured M(w)'s were within ±5% of the expected M(w)'s. A comprehensive model to describe the UF membrane productivity during the treatment of E-stage effluent was developed. This model accounts for variations in membrane, feed water and operational variables. The feed water variables that were incorporated into the model include molecular size distribution, viscosity and concentration. Also, included in the model are the operational variables such as trans-membrane pressure and cross-flow velocity. This model predicted the fluxes for the E- and oxygenated E-stage (E₀) effluents within an error of 9%. The UF membrane fouling by E-stage effluent was quantified employing fouling potential factors. An increase in the molecular weight cut-off (MWCO) of the membranes resulted in increased irreversible fouling possibly by increased pore plugging. Lower irreversible fouling was observed for pulp mill effluents with high M(w)'s. The role of surfactants in reducing the membrane fouling was also discussed. The ratio of M(w) of feed wastewater to the MWCO of the membrane, denoted by λ, effectively represents the ratio of the average diameter of the solute molecule to the nominal diameter of the pore. Membrane rejection and fouling potentials were related to λ. The measured apparent diffusion (D) and mass transfer (k) coefficients for the E- and E₀-stage effluents across the membranes were found to confirm to D ∼ M(w)⁻⁽⁰·³³ ᵗᵒ ⁰·⁴⁸⁾ and k ∼ D⁰·⁶⁶.

The problem of defining sediment supply conditions is of fundamental importance in the prediction of bedload discharge in alluvial channels, because most bedload equations were developed based on the general assumption that the rates at which sediment becomes available for transport equal the sediment-transport capacity of the flow. The classification of availability of sediment on the accuracy and applicability of seven bedload equations in alluvial channels is described and discussed in this dissertation. Historical hydraulic and sedimentological data from 22 alluvial channels of the United States are used to define the sediment-transport regimes and to compare predicted and measured bedload discharges. Exponential relations between sediment supply end energy are used to show if at a reach scale a channel has supply-limited or non-supply limited regime based on the statistical variations of bedload-transport rates with stream power. The root-mean-square error and the inequality coefficients are use to assess the bedload equation's ability to reproduce the trend of the measured values, whereas the discrepancy ratio is used to evaluate the equation's ability to reproduce individual measured data. Relations between the median particle-size ratio, which quantifies the coarseness or fineness of the channel bed, and the discrepancy ratio are used to illustrate process controlling the accuracy of bedload equations. Information presented here shows that an understanding of channel's sediment regime in the process of bedload prediction improves the applicability of bedload equations in alluvial channels.

The objective of this research was to evaluate the impact of bioaugmentation of soil with microorganisms harboring plasmid pJP4 on remediation, plasmid transfer, and plasmid dispersal. Divided into three sections, this research showed that use of microbial inocula harboring self-transmissible plasmids holds promise as an applicable bioremediation approach. In the first study, a pJP4 donor that could readily be counter-selected due to a lack of chromosomal genes necessary for 2,4-dichlorophenoxyacetic acid (2,4-D) mineralization was generated to allow detection of transconjugants in soil. Plasmid pJP4 was introduced into Escherichia coli (ATCC 15224), via plate mating with Ralstonia eutropha JMP134 to create such a donor (E. coli D11). Transfer of Plasmid pJP4 to diverse indigenous populations was detected in soils, and under conditions, where it had not been observed previously. Plexiglass columns were used in the second study to evaluate dissemination of plasmid pJP4 under unsaturated or saturated flow conditions in a 2,4-D contaminated soil. In unsaturated soil, pJP4 was detected in both culturable donor and transconjugant cells extending to 10.5 cm from the inoculated layer. In soil subjected to saturated flow conditions, no transconjugants were detected; however, donors were found throughout the entire length of the column (30.5 cm). Thus, donor transport in conjunction with plasmid transfer to indigenous recipients allowed for significant dissemination of introduced genes through contaminated soil. The last study was conducted using soil contaminated with 2,4-D alone or co-contaminated with 2,4-D and cadmium (Cd). This study assessed the impact of introduction of the pJP4 genes via cell bioaugmentation (R. eutropha JMP134 donor), or via gene augmentation (E. coli D11 donor). Both introduced donors remained culturable and transferred plasmid pJP4 to diverse indigenous recipients. Cell bioaugmentation resulted in the most rapid 2,4-D degradation; however, upon a second exposure to 2,4-D, gene augmentation of indigenous populations was more successful. The presence of Cd (100 μg g dry soil⁻¹) had a minimal impact on 2,4-D degradation and transconjugant formation. The establishment of an array of stable indigenous plasmid hosts may be particularly useful in sites with potential for re-exposure or extensive, and thus, long term contamination.

Forty percent of hazardous waste sites on the U.S. Environmental Protection Agency's National Priority List (NPL) are cocontaminated with organic and metal pollutants. Conventional approaches to remediating these sites are costly and often ineffective. Bioremediation is a promising, cost-effective alternative but metal toxicity at cocontaminated sites may limit its efficacy. The research described in this dissertation provides two new possible approaches to enhance the bioremediation of cocontaminated environments and sheds light on the relationship between metal concentration and inhibition of organic pollutant biodegradation. In Objective 1, a rhamnolipid biosurfactant was employed to increase naphthalene biodegradation in the presence of cadmium. The biosurfactant reduced bioavailable cadmium concentrations and increased naphthalene bioavailability. Neither of these phenomena, however, fully accounted for the ability of rhamnolipid to reduce cadmium toxicity. The ability of rhamnolipid to alter the cell surface appeared critical to its ability to mitigate toxicity. In Objective 2, pH was lowered to increase naphthalene biodegradation in the presence of cadmium. Reductions in pH had previously been reported to mitigate metal toxicity, but the mechanism of such reductions warranted elucidation. Previous studies implicated the formation of monovalent hydroxylated metal in the mechanism by which pH mediates toxicity. Results of this study, however, suggest that the importance of such species in determining toxicity may be much less than that of the increased competition between hydrogen and metal ions for binding sites on the cell surface at reduced pH. An indirect relationship between metal concentration and inhibition of organic biodegradation was revealed in Objective 3. Naphthalene biodegradation was more sensitive to cadmium concentrations of 10 and 37.5 mg/L than 100 mg/L. For this reason, we investigated whether naphthalene biodegradation could be increased in the presence of a toxic concentration of cadmium by raising the total metal concentration to a higher, but relatively less toxic concentration. Only elevated concentrations of zinc reduced cadmium toxicity. High but less toxic levels of metal may more rapidly induce the transcription of a gene(s) important in metal efflux than lower more toxic concentrations.

Aquaculture has great potential to help supply the nutritional needs of a growing population. To date, however, the benefits that aquaculture can have, have largely been overshadowed by the environmental degradation some segments of the industry have caused. The following body of work describes my efforts to help reduce the environmental impacts of aquaculture. By integrating aquaculture production into traditional agriculture, the impact of farming on already limited water resources and the reliance on chemical fertilizers can be reduced. Recent expansion of the aquaculture industry in Arizona has made it possible to study the integration of olive groves with marine shrimp culture. In chapter 3, I describe the characterization and evaluation of the effluent from an inland, low-salinity shrimp farm as a potential source of irrigation water. I found that 0.41 kg of ammonia-nitrogen, 0.698 kg of nitrite-nitrogen, 8.7 kg of nitrate-nitrogen and 0.93 kg of total phosphorus (TP) were made available as fertilizer each day in the effluent water. Based on the results of this first study, I decided to conduct a farm trial to quantify the effects of these shrimp farm effluents on olive trees. This work is described in chapter 4. Trees in all treatment groups grew an average of 40.1 cm over the four month study period. While growth of trees irrigated with shrimp farm effluent did not improve in respect to the other treatments, our results do indicate that irrigating with low-salinity water had no noticeable negative effects. Chapter 5 describes work conducted in Idaho, as part of a larger study aimed at reducing the effluent loads of phosphorus (P) from high density, flow-through aquaculture facilities. Research steps were taken to establish a relationship between TP and the carbon 12/13 isotope ratio (δ¹³C) and/or the nitrogen 14/15 isotope ratio (δ¹⁵N). Our findings suggest that both δ¹⁵N and δ¹³C are good better proxies for P, after correcting for P retention. A linear regression of %P (corrected) on δ¹³C and δ¹⁵N resulted in R2 values of 0.843 and 0.8622, respectively. This suggests that by tracking δ¹⁵N and/or δ¹³C through a high-density, flow-through aquaculture facility over time I will be able to determine the residence time of P with a high degree of accuracy.

The impact of microbial population dynamics on the biodegradation and transport of organic compounds was evaluated in this study. At the laboratory-scale, results from miscible-displacement studies demonstrated that transport and biodegradation behavior in systems with increasing biologic diversity and population density variation was considerably more variable. Biokinetic parameters associated with biodegradation of the target compound were found to be considerably different in batch versus flow-through systems. While growth rates were always higher in the flow-through systems, the impacts on microbial lag and cell yield were opposite in different soils. In homogeneous sand, microbial lag was longer and column cell yields were larger than values reported under batch conditions. However, in more heterogeneous soils, microbial lag was shorter and column yields were smaller in the flow-through systems. This was determined in part using a one-dimensional contaminant transport and biodegradation model that incorporates the effects of microbial lag, inhibition, bacterial transport and nonuniform distribution of microbes, which was developed as a part of this study. In the second part of this study, a contaminant transport and biodegradation model incorporating linear biodegradation was applied to recovery data from small input pulses of biotracers at the field scale. One field site was low in oxygen and fairly homogeneous. The other had been subjected to a surfactant flush that enhanced oxygen concentrations, and thus microbial population densities, near the injection wells. Application of this model allowed for quantitative determination of the spatial distribution of microbial activity at the field sites.

Horseradish peroxidase (HRP) enzyme catalyzes the oxidation of aqueous phenols by hydrogen peroxide resulting in the formation and precipitation of polymeric products. The technical feasibility of this enzymatic process for the treatment of industrial wastewaters that contain phenols was investigated. Bench-scale experiments were conducted in which the influences of selected components in the waste matrix on treatment efficiency were assessed. / Experiments with synthetic phenol solutions revealed that the toxicity of HRP-treated phenol solutions declines with time and is dependent on the presence of protective additives, the mode of reagent addition, and the presence of wastewater constituents. Also, many phenolic solutions can be completely detoxified by providing an additional dose of hydrogen peroxide after the completion of the enzymatic reaction. Chitosan was found to be an effective additive for reducing the amount of enzyme required to accomplish phenol transformation in synthetic and actual wastewaters. / HRP was able to accomplish the treatment of phenols in the presence of a wide range of concentrations of suspended solids, salts, metals, and other inorganic and organic species that are frequently present in industrial wastewaters. In certain instances, treatment was more effective in a real waste matrix as compared to the treatment of pure solutions of phenol due to the presence of particular waste components. However, sulfide, manganese(II) and low quantities of cyanide negatively impacted upon the enzymatic transformation of phenol. / It was demonstrated that actual industrial wastewaters collected from pulp and paper production and petroleum refining operations could be treated with HRP and H2O2 to meet regulatory discharge limits for phenol. The enzymatic process can selectively target phenols, which are a major source of toxicity in the wastes, for treatment. Treatment of real wastewaters may require higher than stoichiometric doses of hydrogen peroxide due to the inherent peroxide demand of reduced wastewater constituents or catalytic decomposition of peroxide. HRP-treatment improved wastewater quality as reflected in a significant toxicity reduction. It can also result in a substantial decrease in the biochemical and chemical oxygen demands.

<p> Communities worldwide face water supply challenges and often seek alternative sources of water. Recycled water is an alternative generated from wastewater to reduce non-potable uses of high quality water supplies for irrigation, industrial processes, power plant cooling, and toilet flushing. Researchers have recommended constructing the systems in new communities to reduce capital investment. The implementation of these systems is often financially difficult to justify within existing communities. Orange County Water District constructed a recycled water system, Green Acres Project (GAP), within existing communities in northern Orange County, California. The system delivers recycled water to four cities, reduces seawater intrusion, creates a benefit from a wastewater stream, and diversifies the region&rsquo;s water portfolio. As is common among recycled systems, the GAP has operated at a financial loss since its construction in the early 1990&rsquo;s. Through water sale revenues and a subsidy program, the District has been able to cover operational and maintenance costs but not capital. This study presents hydraulic and financial modeling to better understand the current GAP system and proposed changes. EPANET has been used to simulate five scenarios that include current operation, known future demand changes, breaking distribution loops, and increasing demand to balance finances. Analyzed financial scenarios include continued operation, breakeven finances, change in treatment technology, abandonment of system, and changing the local definition of recycled water. Recommendations to improve financial and operational efficiencies, challenges, and lessons learned from the GAP system are presented so other communities investigating implementation of recycled water programs may become better informed.</p>

<p> Water vapor, clouds and aerosols are three major components in the atmosphere that largely influence the Earth's climate and weather systems. However, there is still a lack of understanding on the distribution and interaction of these components. Large uncertainties still remain in estimating the magnitude and direction of the aerosol indirect effect on cloud radiative forcing, which potentially can either double or cancel out all anthropogenic greenhouse gas effect. In particular, a small variation in water vapor mixing ratio and cloud distribution in the upper troposphere and lower stratosphere (UT/LS) can generate large impacts on the Earth's surface temperature. Yet the understanding of water vapor and clouds in the UT/LS is still limited due to difficulties in observations. To improve our understanding of these components, observations are needed from the microscale (~100 m) to the global scale. The first part of my PhD work is to provide quality-controlled, high resolution (~200 m), in situ water vapor observations using an open-path, aircraft-based laser hygrometer. The laboratory calibrations of the laser hygrometer were conducted using complementary experimental systems. The second part is to compare the NASA AIRS/AMSU-A water vapor and temperature retrievals with aircraft-based observations from the surface to the UT/LS at 87&deg;N-67&deg;S in order to understand the accuracy and uncertainties in remote sensing measurements. The third part of my research analyzes the spatial characteristics and formation condition of ice supersaturation (ISS), the birthplace of cirrus clouds, and shows that water vapor horizontal heterogeneities play a key role in determining the spatial distribution of ISS. The fourth part is to understand the formation and evolution of ice crystal regions (ICRs) in a quasi-Lagrangian view. Finally, to help estimate the hemispheric differences in ice nucleation, the ISS distribution and ICR evolution are compared between the two hemispheres. Overall, these analyses provided a microphysical scale yet global perspective of the formation of ISS and cirrus clouds. Ultimately, these efforts will help to improve the understanding of human activities' influences on clouds, water vapor and relative humidity in the UT/LS and provide more accurate representations of these components in future climate prediction.</p>

Studies are presented investigating the metabolism of 2,4,6-trinitrotoluene (TNT) by Clostridium acetobutylicum. When incubated with a batch culture of acetogenic Clostridium acetobutylicum, TNT was reduced through 4-hydroxylamino-2,6-dinitrotoluene (and to a lesser extent 2-hydroxylamino-4,6-dinitrotoluene) to 2,4-dihydroxylamino-6-nitrotoluene. The intermediate 2,4-dihydroxylamino-6-nitrotoluene then underwent a microbially catalyzed Bamberger rearrangement to form 4-amino-6-hydroxylamino-4-methyl-2-nitrophenol. When incubated with TNT-contaminated soil, C. acetobutylicum was able to transform TNT to 2,4-dihydroxylamino-6-nitrotoluene and beyond. Additionally, aerobic soil bacteria indigenous to TNT contaminated soil were able to mineralize a fraction (approximately 9% to 10%) of the products created by the reduction of TNT by C. acetobutylicum.